Re: [PATCH v8 6/8] OF: i2c: Add OF notifier handler

[Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>]

Hi Grant,

> On Nov 21, 2014, at 17:08 , Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> wrote:
> 
> On Thu, 20 Nov 2014 18:03:33 -0800
> , Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
> wrote:
>> On 11/20/2014 05:53 PM, Grant Likely wrote:
>>> On Tue, 28 Oct 2014 22:36:03 +0200
>>> , Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
>>>  wrote:
>>>> Add OF notifier handler needed for creating/destroying i2c devices
>>>> according to dynamic runtime changes in the DT live tree.
>>>> 
>>>> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
>>>> ---
>>>>  drivers/i2c/i2c-core.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++-
>>>>  1 file changed, 78 insertions(+), 1 deletion(-)
>>>> 
>>>> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
>>>> index e6da9d3..e751b78 100644
>>>> --- a/drivers/i2c/i2c-core.c
>>>> +++ b/drivers/i2c/i2c-core.c
>>>> @@ -1470,6 +1470,7 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
>>>>  	return i2c_verify_adapter(dev);
>>>>  }
>>>>  EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
>>>> +
>>>>  #else
>>>>  static void of_i2c_register_devices(struct i2c_adapter *adap) { }
>>>>  #endif /* CONFIG_OF */
>>>> @@ -1955,6 +1956,71 @@ void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
>>>>  }
>>>>  EXPORT_SYMBOL(i2c_clients_command);
>>>> 
>>>> +#if IS_ENABLED(CONFIG_OF)
>>>> +
>>>> +static int of_i2c_notify(struct notifier_block *nb,
>>>> +				unsigned long action, void *arg)
>>>> +{
>>>> +	struct device_node *dn;
>>>> +	struct i2c_adapter *adap;
>>>> +	struct i2c_client *client;
>>>> +	int state;
>>>> +
>>>> +	state = of_reconfig_get_state_change(action, arg);
>>>> +	if (state == -1)
>>>> +		return NOTIFY_OK;
>>>> +
>>>> +	switch (action) {
>>>> +	case OF_RECONFIG_ATTACH_NODE:
>>>> +	case OF_RECONFIG_DETACH_NODE:
>>>> +		dn = arg;
>>>> +		break;
>>>> +	case OF_RECONFIG_ADD_PROPERTY:
>>>> +	case OF_RECONFIG_REMOVE_PROPERTY:
>>>> +	case OF_RECONFIG_UPDATE_PROPERTY:
>>>> +		dn = ((struct of_prop_reconfig *)arg)->dn;
>>>> +		break;
>>>> +	default:
>>>> +		return NOTIFY_OK;
>>>> +	}
>>>> +
>>>> +	if (state) {
>>>> +
>>>> +		adap = of_find_i2c_adapter_by_node(dn->parent);
>>>> +		if (adap == NULL)
>>>> +			return NOTIFY_OK;	/* not for us */
>>>> +
>>>> +		client = of_i2c_register_device(adap, dn);
>>>> +		put_device(&adap->dev);
>>>> +
>>>> +		if (IS_ERR(client)) {
>>>> +			pr_err("%s: failed to create for '%s'\n",
>>>> +					__func__, dn->full_name);
>>>> +			return notifier_from_errno(PTR_ERR(client));
>>>> +		}
>>>> +
>>>> +	} else {
>>>> +
>>>> +		/* find our device by node */
>>>> +		client = of_find_i2c_device_by_node(dn);
>>>> +		if (client == NULL)
>>>> +			return NOTIFY_OK;	/* no? not meant for us */
>>>> +
>>>> +		/* unregister takes one ref away */
>>>> +		i2c_unregister_device(client);
>>>> +
>>>> +		/* and put the reference of the find */
>>>> +		put_device(&client->dev);
>>>> +
>>>> +	}
>>> 
>>> Nit: odd whitespace
>>> 
>>>> +
>>>> +	return NOTIFY_OK;
>>>> +}
>>>> +
>>>> +static struct notifier_block i2c_of_notifier;
>>>> +
>>>> +#endif
>>>> +
>>>>  static int __init i2c_init(void)
>>>>  {
>>>>  	int retval;
>>>> @@ -1972,8 +2038,19 @@ static int __init i2c_init(void)
>>>>  	retval = i2c_add_driver(&dummy_driver);
>>>>  	if (retval)
>>>>  		goto class_err;
>>>> -	return 0;
>>>> 
>>>> +#if IS_ENABLED(CONFIG_OF)
>>>> +	i2c_of_notifier.notifier_call = of_i2c_notify;
>> 
>> Wouldn't it be easier to just initialize i2c_of_notifier above instead of
>> here in the code ? Or is there a reason for doing it here ?
> 
> Yes, absolutely. This code should also depend on CONFIG_OF_DYNAMIC too,
> not merely CONFIG_OF.
> 
>> 

No reason; it just seemed like the most opportune place to put it at the time.

>> Thanks,
>> Guenter
>> 
>>>> +	retval = of_reconfig_notifier_register(&i2c_of_notifier);
>>>> +	if (retval)
>>>> +		goto notifier_err;
>>>> +#endif
> 
> We can also get rid of the ugly #ifdef in the body by creating empty
> stubs for of_reconfig_notify_{register,unregister}() and doing the
> following:
> 
> 	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
> 		WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier))
> 
> I picked up the patch into my tree and made the above changes because
> they're pretty trivial. If Wolfram is okay with it then I can take the
> whole series through my tree. Otherwise I'll put the of_reconfig_* empty
> stubs into a separate branch that he and broonie can both pull.
> 

I’m fine with doing this if you’d like, it’s pretty simple.

Regards

— Pantelis

> g.
> 
>>>> +
>>>> +	return 0;
>>>> +#if IS_ENABLED(CONFIG_OF)
>>>> +notifier_err:
>>>> +	i2c_del_driver(&dummy_driver);
>>>> +#endif
>>> 
>>> Similar to my comment on the platform bus, don't break the entire bus if
>>> registration of the notifier fails. I would drop the error case and just
>>> do a WARN_ON() if it fails.
>>> 
>>> Otherwise:
>>> 
>>> Acked-by: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
>>> 
>>>>  class_err:
>>>>  #ifdef CONFIG_I2C_COMPAT
>>>>  	class_compat_unregister(i2c_adapter_compat_class);
>>>> --
>>>> 1.7.12
>>>> 
>>> 
>>> 
>> 
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